49ers’ A.J. Jenkins likely to make debut

Finally, in the 13th game of his rookie season, 49ers wide receiver A.J. Jenkins might step onto the field. Mario Manningham, nursing a shoulder injury, missed practice Friday and was listed as doubtful for Sunday’s game against Miami. Kyle Williams already is out with his season-ending torn ACL, so the 49ers are getting thinner and thinner at the position.

This should create a long-awaited chance for Jenkins, the team’s first-round draft choice from Illinois. Michael Crabtree and Randy Moss are still ahead of Jenkins, and so is Ted Ginn Jr., but the 49ers are likely to use more than three wide receivers.

He then elaborated on Jenkins’ development in practice in recent weeks, saying, “I’ve seen progress from A.J. He’s been on his assignments, and he’s executed well when he’s been out there. He’s giving great effort, and football rewards that effort.”

Jenkins has suited up for two games this season, Sept. 9 in Green Bay and last Sunday in St. Louis. He didn’t play in either game.

Bouncing back: Before their loss to the Rams, the 49ers had dropped five games and tied one under Harbaugh. All six times, they came back and won the next week.

This pattern will be tested once more against the Dolphins.

“You’re ticked off,” Harbaugh said of the practice-week vibe after a loss. “Usually, you’re going to do one of two things – come back and do something about it or cower in the corner and curl up in the fetal position. So let’s come out and do something about it.”

Briefly: The NFL issued fines of $10,000 to linebacker NaVorro Bowman (unnecessary roughness) and $7,875 to safety Dashon Goldson (roughing the passer) for infractions against the Rams. … The 49ers listed 10 players as probable on their injury report, including running back Frank Gore (wrist), linebacker Patrick Willis (shoulder) and kicker David Akers (pelvis).